We employed CE to identify mixtures of the toxic alkaloids lappaconitine, bullatine A, atropine sulfate, atropine methobromide, scopolamine hydrobromide, anisodamine hydrobromide, brucine, strychnine, quinine sulfate, and chloroquine in human blood and urine, using procaine hydrochloride as an internal standard. The separation employed a fused-silica capillary of 75 microm id x 60 cm length (effective length: 50.2 cm) and a buffer containing 100 mM phosphate and 5% ACN (pH 4.0). The sample was injected in a pressure mode and the separation was performed at a voltage of 16 kV and a temperature of 25 degrees C. The compounds were detected by UV absorbance at wavelengths of 195 and 235 nm. All the ten alkaloids were separated within 16 min. The method was validated with regard to precision (RSD), accuracy, sensitivity, linear range, LOD, and LOQ. In blood and urine samples, the detection limits were 5-40 ng/mL and linear calibration curves were obtained over the range of 0.02-10 microg/mL. The precision of intra- and interday measurements was less than 15%. Electrophoretic peaks could be identified either by the relative migration time or by their UV spectrum. 相似文献
An approach to organic-inorganic interfacial structure at the atomic level is a great challenge in the studies of biomineralization. We demonstrate that atomic force microscopy (AFM) is powerful tool to discover the biomineral interface in detail. By using a model system of (100) hydroxyapatite (HAP) face and citrate, it reveals experimentally that only a side carboxylate and a surface calcium ion are involved in the binding effect during the citrate adsorption, which is against the previous understandings by using Langmuir adsorption and computer simulation. Furthermore, the adsorbed citrate molecules can use their free carboxylate and hydroxyl groups to be self-assembled on the HAP surface. AFM examination also finds that the presence of citrate molecules on the HAP crystal faces can enhance the adhesion force of the HAP surface. We suggest that the established AFM method can be used for a precise and direct understanding of biointerfaces at the atomic level. 相似文献
Li2ZnTi3O8/C nanocomposite has been synthesized using phenolic resin as carbon source in this work. The structure, morphology, and electrochemical properties of the as-prepared Li2ZnTi3O8 samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), Raman spectroscopy (RS), galvanostatic charge–discharge, and AC impedance spectroscopy. SEM images show that Li2ZnTi3O8/C was agglomerated with a primary particle size of ca. 40 nm. TEM images reveal that a homogeneous carbon layer (ca. 5 nm) formed on the surface of Li2ZnTi3O8 particles which is favorable to improve the electronic conductivity and inhibit the growth of Li2ZnTi3O8 during annealing process. The as-prepared Li2ZnTi3O8/C composite with 6.0 wt.% carbon exhibited a high initial discharge capacity of 425 and 159 mAh g?1 at 0.05 and 5 A g?1, respectively. At a high current density of 1 A g?1, 95.5 % of its initial value is obtained after 100 cycles. 相似文献
Microchimica Acta - We report on a novel strategy for the electrochemical detection of cocaine. It is based on the use of a supramolecular aptamer, rolling circle amplification (RCA), and multiplex... 相似文献
We describe a new kind of electrochemical immunoassay for the peptide hormone prolactin. A glassy carbon electrode (GCE) was modified with a hybrid material consisting of graphene, single walled carbon nanotubes and gold nanoparticles (AuNPs) in a chitosan (CS) matrix. The graphene and the single wall carbon nanotubes were first placed on the GCE, and the AuNPs were then electrodeposited on the surface by cyclic voltammetry. This structure results in a comparably large surface for immobilization of the capturing antibody (Ab1). The modified electrode was used in a standard sandwich-type of immunoassay. The secondary antibody (Ab2) consisted of AuNPs with immobilized Ab2 and modified with biotinylated DNA as signal tags. Finally, alkaline phosphatase was bound to the biotinylated DNA-AuNPs-Ab2 conjugate via streptavidin chemistry. The enzyme catalyzes the hydrolysis of the α-naphthyl phosphate to form α-naphthol which is highly electroactive at an operating voltage as low as 180 mV (vs. Ag/AgCl). The resulting immunoassay exhibits high sensitivity, wide linear range (50 to 3200 pg∙mL‾1), low detection limit (47 pg∙mL‾1), acceptable selectivity and reproducibility. The assay provides a pragmatic platform for signal amplification and has a great potential for the sensitive determination of antigens other than prolactine.
The immunoassay for prolactin is based on a glassy carbon electrode modified with SWCNTs, graphene and antibody-coated gold nanoparticles, and a secondary antibody conjugated to other gold nanoparticles via a biotinylated DNA linker
Two DendriMac polymers (Dendri‐hydr and Dendri‐click) are efficiently and conveniently synthesized via the combination of living anionic polymerization (LAP) and hydrosilylation/click chemistry. Based on the end‐capping of DPE derivatives (DPE‐SiH and DPE‐DA) toward polymeric anions, the polymeric core and arms are effectively synthesized, and the base polymers can be regarded as polymeric bricks. Hydrosilylation and click chemistry are used as coupling reactions to construct the DendriMac polymers with high efficiency and convenience. The numbers of branched arms are calculated by SEC as 5.84 and 6.08 for Dendri‐hydr and Dendri‐click, respectively, which indicate that the DendriMac architectures exhibit high structural integrity. Because of its independence, high efficiency, and convenience, the whole construction can be regarded as the “building of polymeric bricks.”
In the title complex of [Ni(C3H4N2)6](C8H7O3)2, the Ni atom is in an octahedral environment formed by the tertiary N atom of the imidazole moieties. The methoxybenzoate moieties act as a bridge connecting two hexakis(imidazole)nickel(II) molecules through N—H?O hydrogen bonds. 相似文献